Monday, September 12, 2016

A Misguided case of "Transit First"?

Many cities adopted Portland's, (OR) transportation priorities that put pedestrians, transit and bicycles ahead of cars. Those cities remodeled their streets around those re-stacked priorities in what is typically called a Complete Streets policy. Baltimore has such a policy in place, too, but it hasn't been implemented. A transit first policy simply hasn't happened yet in Baltimore.

Until now. Finally we have a precedent for an actual implementation of a transit before cars policy, but it isn't clear that the City will get a lot of praise for it.

The unlikely application of the policy: The Westside sinkhole on Mulberry Street (US 40 eastbound) and the measures to prepare for a fix. The installation of temporary surface sewer main detour along Franklin Street (US 40 westbound) came to a screeching halt at Howard Street because of transit. The question: how to cross the light rail tracks without disrupting trains.

In applying transit first, it was decided that the 25,000 or so August light rail riders couldn't be inconvenienced with a solution that would cut the tracks. Not for a few days and even less for a few months. So instead of putting the temporary sewer pipes in a shallow trench that is covered with steel plates so cars can roll over them as it was done at intersections without rail, the engineers went back to the drawing boards and a lot of head scratching and investigating. After months of deliberation and obtaining permits they came up with a solution that is reminiscent of building the tunnel-section of the cancelled Red Line: A combination of open cut and cover and underground boring.

The result: a hole in the middle of Franklin Street that is bigger and deeper than the sinkhole in Mulberry Street and took weeks to create.

The neatly framed out gigantic pit in the middle of West Franklin Street. At bottom see assembled boring machine that advances the pipes deep under Howard Street. The yellow scaffold is a staircase for workers to reach the bottom.
 (Photo ArchPlan)

The problems with this transit first decision are numerous:
  • This exercise happens in the middle of Franklin Street and closes the street for about two months,
  • Busy route 40 with an order of 25,000-30,000 vehicles in each direction per day is closed both ways, at Mulberry and at Franklin Streets.
  • While the sewer detour remains disconnected, sewer spills untreted into the Inner Harbor, during rainstorms in signficant quantities.
  • the pit that is needed to place a tunnel boring machine 25' below street level is an extravagant 24/7 engineering  fete that requires piles, steel plates, huge excavators, vacuuming and cranes that lift equipment in and out that seems completely out of proportion for placing a temporary sewer pipe so a sinkhole can be fixed
  • the cost of the boring exercise is not provided, since all work is performed on time and material (T&M). The SUN reported that the Centre Street and Mulberry sinkhole repairs combined are estimated to cost over $10 million, $6-7 million for Mulberry Street alone. The tunnel boring is the most complicated part of this followed by the cost for lining the full stretch of the sewer line with liquid plastic to reinforce it against future failure.  I would estimate that the mini tunnels will cost at least $1-2 million if not more.
The pipe being pushed into the bored hole under Hoard Street (still
above the Howard Street tunnel)
The alternative to the tunnel would have been the usual shallow trench that would have cut the rails.

The 2' concrete slab that carries and embeds the rails could have been replaced within days and could have been poured around the shallow steel pipes reinstating the full structural integrity of the slab and rails within a week. During that week rail passengers could have dis-boarded on one side of the construction area and boarded a waiting train on the other.

Possibly this may have meant to disrupt the shuttle service to Penn Station in order to get the necessary train cars to do this; similar operations with bus bridges in between have been done before.
Again, the cost for this short term construction and altered LRT operation is only a wild guess, but I would place it in the range of $100-200,000 at the most, i.e. one tenth of the pipe tunneling with a disruption or inconvenience of a smaller number of people over a much shorter time.

Transit first should not be a policy in which Peter is robbed to pay Paul and it shouldn't be executed on the backs of the environment, businesses and residences around what has become an enormous construction site when it could have been much less of an imposition. 
Regular pipe crossing at intersection with steel plates
(photo: ArchPlan Inc.)

The biggest irony of all of this: Mulberry Street had been trenched  for placing a new water main only three weeks or so before the sinkhole occurred. That new water main never went life before the street collapsed. The trench had given a good view of what was going on under the concrete street cover. From what I was told reports of cavities and wash-outs were followed by instructions to just fill the voids up again.

The reason was classic cars first policy: Mulberry was a street too busy to be closed for a proper investigation.

Klaus Philipsen, FAIA

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